1. ATMS600v3 SensAqua AS Remote sensing in aquatic systems
The SensAqua Automatic Trace Metal monitoring System for remote, unattended, automatic and continuous monitoring of heavy metals
A measuring station under a bridge
The ATMS600v3 Technical Specifications
The ATMS600v3 consists of one cabinet, inside is a smaller unit with the main electronics and the water system with pumping stirring and draining and the measuring cell with electrodes. As an option, an additional water system can be connected.
The ATMS600 is run by a microprocessor unit and not by a computer. Howev- er, a computer is needed for starting up, input/output and graphical presenta-
tions.
Electrode system: Patented Alloys Silver/Silver Chloride Platinum
Software: POS V1.5 (or above) running Windows 2000™/XP/Vista/7 (32 or 64 bit)
Data storage: Compact Flash Card (CF) or computer
Dimension: 40 x 30 x 17 cm
(ATMS600v3D 60 x 30 x 17 cm)
Weight: 8 kg, (ATMS600D 12 kg) Power Supply: 12 V DC (or adapter) Polarization: Voltage range: ± 5 V
Sweep Types: Differential Pulse/SquareWave/Staircase Sweep Direction: Anodic/Cathodic
Min. Sweep Step Height: 5/8 mV
Min Sweep Step duration: 10 ms
Measurements
ATMS600v3
Also available as a dual-cell version, ATMS600v3D, and as a low-cost non-automatic version for laboratory use,
From an integrated measuring station in Poland
Quantification of several different metals using one or two sensors (Zn, Pb, Cd, Ni, Co, Tl, Hg, As etc.) in the ppb level
Environmental friendly non-toxic electrodes and chemicals
High sensitivity, down to 1 ppb (1 µg/L), with typical measuring accuracy ± 10 % at 10 ppb
Automatic updating of software and firmware on Internet
Stable over time, typical one month without attendance
Simple maintenance, with all electronics on one microprocessor card
Short time for each analysis (2-5 minutes)
Almost neglectable operating costs and maintenance
Compact wall version, but can also be supplied as a complete floor cabinet or as a simplified version for manual use in a laboratory. Integrated automatic systems can also be offered, also to measure pH, TOC, conductivity etc.
User friendly calibration
Automated sampling pretreatment and analysis
Automatic electrochemical cleaning of electrodes
Quantification of various metal forms (species)
Small sample volume (35 mL)
Simple and user friendly software for equipment control and presentation of results
Real time/on-line data presentation, if wanted on the Internet
Input impedance: > 10 Ω
Current ranges: ±2 µA, 20 µA, 200 µA Resolution Current measurement: 16-bit Resolution Feedback: 16-bit Voltammetry
Linear Scan, CV, Differential Pulse, Square Wave, Anodic/Cathodic Stripping
Communication
USB/RS232
Communication over Modbus in RTU mode
Mode LAN Data delivery through web services or TCP direct mA
SMS warning 9
No liquid mercury No mercury salts No toxic materials
Further information:
Tel

2. The ATMS600 can be monitored automatically by using Internet
VOLTAMMETRY is an electroanalytical method where met- als or other species are determined through their redox and diffu- sion properties, like. for the reduction of zinc ions or oxidation of solid zinc metal to Zn2+ ions:
Zn e- = Zn(s) or Zn(s) = Zn e-
This is a very sensitive analysis technique that is very suited for the detection of heavy metals for online and automatic monitoring as no other methods can be used for such purposes. Voltammetry is fast, simple and has low analysis costs. The instruments re- quired are also low cost relative to ICP, ICP-MS and chromato- graphic methods. The method has good sensitivity and a detection limit for the most important heavy metals in the lower ppb region or lower. As a result, the method is suitable for use in analyses of drinking water, industrial processes etc.
The main advantage with this method, compared with other meth- ods, is that this can be used for unmanned remote monitoring
A three-electrode system with a working elec- trode, a reference electrode and a counter electrode is used. The reference electrode is used to control a given potential over time profile vs. the working electrode at zero cur- rent. The current flow is measured between the working electrode and the counter elec- trode, and a voltage is applied there to obtain the mentioned time profile.
There are many different voltammetric tech- niques, depending upon the given time pro-
file. The most common are Linear Scan Volt- ammetry, Square Wave Voltammetry and
Differential Pulse Voltammetry.
Stripping Voltammetry is amongst the most sensitive procedures when combined with one of the mentioned techniques. Using this meth- od, the metal is initially reduced to the solid metal that is deposited on the surface of the working electrode and thus enriched, fol- lowed by an oxidation of that metal. Higher sensitivity can be achieved by increasing the deposition time.
One serious problem in voltammetry is the side reaction:
2H+ + 2e- = H2(g)
as this will give an interfering electrical cur- rent. This current has traditionally been sup- pressed by using a measuring electrode of liq- uid mercury or a mercury film electrode, this in turn being made from a mercury salt. This is because mercury has a very high overpo- tential relative to hydrogen.
Neither liquid mercury nor a mercury salt can be accepted due to the toxicity, in particu- lar for off-laboratory use. Extensive research has been performed internationally for years to find alternative electrode materials.
The breakthrough came in when re- searchers at Norwegian University of Science and Technology NTNU, Department of Chemistry, Trondheim, Norway found that certain solid alloys had positive properties for suppressing the mentioned hydrogen reaction. This has been further developed and is pa- tented internationally.
The ATMS for remotely and unattended to monitor heavy metals in water and effluents is
based on comprehensive documentation, pub- lications and presentations being available on
request.
Electrodes
Measuring cell with electrodes
From the programming panel
Typical results of measurements over time in a river close to a mining area in Norway
A typical voltammetric curve
Actual groups of users
Five requirements are needed for making such automatic voltammetric analyses useful:
Private and public institutions – surveillance of quality of municipal drinking water and effluents
Already established automatic monitoring stations, also to include heavy metals
Metal and metallurgical industry
Terminated industrial areas and mines
Construction work
Oil and shipping
Solid waste and incineration plants
Sea farming
Fundamental research and laboratory use
Sufficient high overvoltage to allow the measurements without interferences from hydrogen gas formation
Sufficient long term stability without need of mainte- nance
Sufficient sensitivity to allow monitoring of trace pollu- tants
That non-toxic material is used (very important for off-
laboratory methods)
Not too expensive material needed
Principle for a three electrode system
The ATMS600 can be monitored automatically by using Internet

3. ATMS600v3
General detection limit in natural water (drinking water and pure lake water) is in the low ppb area. Some approximate guiding electro labile values using differential pulse anodic stripping voltammetry
Metal to de- tect
Working Elec- trode
Supporting electrolyte (high purity chemicals needed)
Ep (V) 1)
Det. Limit 2)
Ligand to add
Mn(II)
Solid silver alloy
Ammonium chloride buffer (pH 6.4) (or NH4Cl 0.02 M)
-1.45
< 5 ppb
Zn(II)
-1.05
Cd(II)
-0.65
Pb(II)
-0.50
< 2 ppb
Tl(I)
Acetate buffer pH 6.4
-0.75
Bi(III)
Ammonium chloride buffer (pH 3)(or NH4Cl 0.02 M)
-0.35
< 10 ppb
Cu(II)
Solid gold alloy
HCl (0.01 M)
+0.25
< 1 ppb
Ni(II)
Ammonium chloride buffer (pH 9.6)
-0.95
DMG4)
Co(II)
-1.15
Hg(II)
HNO3 (10 mM) and HCl (10 mM)
+0.55
Cr(VI)
HCl (0.1 M)
As(III)
HCl (0.2 M)
+0.15
Fe(II)/Fe(III)
Tri-sodium citrate 5.5 hydrate or NH4Cl (0.02 M)
-0.80
DMG = Dimethylglyoxime. Deposition time = 360 s 2)
1) Peak potentials (Ep) might differ in accordance to used reference electrode (RE), (table values against newly made Ag-AgCl/KCl 3 M RE). (Counter electrode is Platinum).
2) For increased sensitivity the deposition time can be expended, but deposition time longer than 1800 seconds is not recommended. Further in- crease of the sensitivity can also be obtained by using square wave voltammetry.
3) By adsorptive differential pulse cathodic stripping voltammetry (deposition potential at – 0.75 V for 60 s).
4) If Ni(II) and Co(II) is present simultaneously in the sample; use a mixture of DMG (0.3 mM), oxine (0.02 mM) and nioxime (0.01 mM). (Maximum number of metals detected simultaneously is five metal, including Mn(II), Zn(II), Cd(II), Pb(II) and Cu(II) (on Solid silver alloy Working Electrode).